This invention relates generally to heat transfer devices, and more particularly to a unique forced convection heat transfer device.
Refrigerated containers and other heat transfer devices are utilized for a wide variety of applications, including household refrigerators, grocery display cabinets, convection heaters, and coolers for storing, preserving, and providing ready access to food items. Such coolers often use forced air convection provided by generating an air flow which passes through a heat exchanger to cool the air flow, and then forcing that air to pass over objects held in the cooler, thus cooling them by convection.
Most refrigerated containers, such as for example a milk cooler for containing a number of milk cartons, are constructed as a thermally insulated cabinet defining a product storage chamber and having an upper access opening, sometimes also having a door for closing the access opening and preventing free heat transfer between the storage chamber and ambient air. However, even those coolers equipped with an access door are often left open for extended periods of time, resulting in free heat transfer by convection between the storage chamber and ambient air, causing enormous energy efficiency losses and warming the product which is in the storage chamber.
It is generally desirable to maintain the entire volume of the container at temperatures equal to or below 40.degree. F., yet also at temperatures above 32.degree. F. to prevent the product from freezing. However, when the access door is open for a long period of time, previous refrigerated containers were generally unable to maintain the temperature of product disposed near the upper access opening below 40.degree. F., without also cooling the products at the bottom of the cooler below 32.degree. F., often causing the food product in the bottom region of the cooler to freeze.
The present invention overcomes this problem by providing a novel apparatus and method for cooling or heating different regions of a container at different heat transfer rates. In the case of a refrigerated container, the lower region of the refrigerated container is cooled by a first fluid flow. The upper region of the container is cooled by a colder curtain of fluid flowing across the access opening, which has been cooled to a lower temperature than the first fluid flow. Of course, the present invention may also be used to heat different areas of a container at different rates.
The heat transfer device of the present invention includes a fan or other powered means for creating a fluid flow, a heat exchanger, and direction controlling surfaces for directing the fluid toward and through a first portion of the heat exchanger, thereby changing the temperature of the fluid. The direction controlling surfaces then direct a portion of the fluid through a second portion of the heat exchanger, thereby causing that portion to undergo a greater temperature change than the remainder of the fluid.
It is therefore an object of the present invention to provide a unique heat transfer device utilizing forced fluid convection through one heat exchanger which changes the temperature of a plurality of fluid flows in different amounts, whereby the aforementioned problems encountered with known systems are overcome.
These and other advantages and features will become apparent from the following description and claims in conjunction with the accompanying drawings.